Beam Pattern Evolution of Accreting X-Ray Pulsar 1A 0535+262 during Its 2020 Giant Outburst
We report on pulse profile decomposition analysis of bright transient X-ray pulsar 1A 0535+262 using broadband Insight-HXMT observations during a giant outburst of the source in 2020. We show that the observed pulse profile shape can be described in terms of a combination of two symmetric single-pol...
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/acbc7a |
| _version_ | 1797701384150188032 |
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| author | Y. F. Hu L. Ji C. Yu P. J. Wang V. Doroshenko A. Santangelo I. Saathoff S. N. Zhang S. Zhang L. D. Kong |
| author_facet | Y. F. Hu L. Ji C. Yu P. J. Wang V. Doroshenko A. Santangelo I. Saathoff S. N. Zhang S. Zhang L. D. Kong |
| author_sort | Y. F. Hu |
| collection | DOAJ |
| description | We report on pulse profile decomposition analysis of bright transient X-ray pulsar 1A 0535+262 using broadband Insight-HXMT observations during a giant outburst of the source in 2020. We show that the observed pulse profile shape can be described in terms of a combination of two symmetric single-pole contributions for a wide range of energies and luminosities for a fixed geometry defining the basic geometry of the pulsar. This corresponds to a slightly distorted dipole magnetic field, i.e., one pole has to be offset by ∼12° from the antipodal position of the other pole. We reconstruct the intrinsic beam patterns of the pulsar assuming that the geometry is recovered from the decomposition analysis, and we find evidence for a transition between “pencil” and “fan” beams in energy ranges above the cyclotron line energy, which can be interpreted as a transition from sub- to supercritical accretion regimes associated with the onset of an accretion column. At lower energies, however, the beam pattern appears to be more complex and contains a substantial “fan” beam and an additional “pencil” beam component at all luminosities. The latter is not related to the accretion rate and is stronger in the fading phase of the outburst. We finally discuss the results in the context of other observational and theoretical findings earlier reported for the source in the literature. |
| first_indexed | 2024-03-12T04:35:54Z |
| format | Article |
| id | doaj.art-41a1c7dc89d342bcaa695b478a31f302 |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-12T04:35:54Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj.art-41a1c7dc89d342bcaa695b478a31f3022023-09-03T09:56:17ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-01945213810.3847/1538-4357/acbc7aBeam Pattern Evolution of Accreting X-Ray Pulsar 1A 0535+262 during Its 2020 Giant OutburstY. F. Hu0L. Ji1C. Yu2https://orcid.org/0000-0003-0454-7890P. J. Wang3V. Doroshenko4A. Santangelo5I. Saathoff6S. N. Zhang7S. Zhang8L. D. Kong9School of Physics and Astronomy, Sun Yat-Sen University , Zhuhai, 519082, People's Republic of China ; jilong@mail.sysu.edu.cn, yucong@mail.sysu.edu.cnSchool of Physics and Astronomy, Sun Yat-Sen University , Zhuhai, 519082, People's Republic of China ; jilong@mail.sysu.edu.cn, yucong@mail.sysu.edu.cnSchool of Physics and Astronomy, Sun Yat-Sen University , Zhuhai, 519082, People's Republic of China ; jilong@mail.sysu.edu.cn, yucong@mail.sysu.edu.cnUniversity of Chinese Academy of Sciences , Chinese Academy of Sciences, Beijing 100049, People's Republic of China; Key Laboratory of Particle Astrophysics, Institute of High Energy Physics , Chinese Academy of Sciences, Beijing 100049, People's Republic of ChinaInstitut für Astronomie und Astrophysik , Kepler Center for Astro and Particle Physics, Eberhard Karls, Universität, Sand 1, D-72076 Tübingen, GermanyInstitut für Astronomie und Astrophysik , Kepler Center for Astro and Particle Physics, Eberhard Karls, Universität, Sand 1, D-72076 Tübingen, GermanyInstitut für Astronomie und Astrophysik , Kepler Center for Astro and Particle Physics, Eberhard Karls, Universität, Sand 1, D-72076 Tübingen, GermanyUniversity of Chinese Academy of Sciences , Chinese Academy of Sciences, Beijing 100049, People's Republic of China; Key Laboratory of Particle Astrophysics, Institute of High Energy Physics , Chinese Academy of Sciences, Beijing 100049, People's Republic of ChinaKey Laboratory of Particle Astrophysics, Institute of High Energy Physics , Chinese Academy of Sciences, Beijing 100049, People's Republic of ChinaUniversity of Chinese Academy of Sciences , Chinese Academy of Sciences, Beijing 100049, People's Republic of China; Key Laboratory of Particle Astrophysics, Institute of High Energy Physics , Chinese Academy of Sciences, Beijing 100049, People's Republic of ChinaWe report on pulse profile decomposition analysis of bright transient X-ray pulsar 1A 0535+262 using broadband Insight-HXMT observations during a giant outburst of the source in 2020. We show that the observed pulse profile shape can be described in terms of a combination of two symmetric single-pole contributions for a wide range of energies and luminosities for a fixed geometry defining the basic geometry of the pulsar. This corresponds to a slightly distorted dipole magnetic field, i.e., one pole has to be offset by ∼12° from the antipodal position of the other pole. We reconstruct the intrinsic beam patterns of the pulsar assuming that the geometry is recovered from the decomposition analysis, and we find evidence for a transition between “pencil” and “fan” beams in energy ranges above the cyclotron line energy, which can be interpreted as a transition from sub- to supercritical accretion regimes associated with the onset of an accretion column. At lower energies, however, the beam pattern appears to be more complex and contains a substantial “fan” beam and an additional “pencil” beam component at all luminosities. The latter is not related to the accretion rate and is stronger in the fading phase of the outburst. We finally discuss the results in the context of other observational and theoretical findings earlier reported for the source in the literature.https://doi.org/10.3847/1538-4357/acbc7aX-ray binary stars |
| spellingShingle | Y. F. Hu L. Ji C. Yu P. J. Wang V. Doroshenko A. Santangelo I. Saathoff S. N. Zhang S. Zhang L. D. Kong Beam Pattern Evolution of Accreting X-Ray Pulsar 1A 0535+262 during Its 2020 Giant Outburst The Astrophysical Journal X-ray binary stars |
| title | Beam Pattern Evolution of Accreting X-Ray Pulsar 1A 0535+262 during Its 2020 Giant Outburst |
| title_full | Beam Pattern Evolution of Accreting X-Ray Pulsar 1A 0535+262 during Its 2020 Giant Outburst |
| title_fullStr | Beam Pattern Evolution of Accreting X-Ray Pulsar 1A 0535+262 during Its 2020 Giant Outburst |
| title_full_unstemmed | Beam Pattern Evolution of Accreting X-Ray Pulsar 1A 0535+262 during Its 2020 Giant Outburst |
| title_short | Beam Pattern Evolution of Accreting X-Ray Pulsar 1A 0535+262 during Its 2020 Giant Outburst |
| title_sort | beam pattern evolution of accreting x ray pulsar 1a 0535 262 during its 2020 giant outburst |
| topic | X-ray binary stars |
| url | https://doi.org/10.3847/1538-4357/acbc7a |
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